High voltage, negative polarity, regulated power supply



R. G. LUEBBEN Jan. 5, 1965 HIGH VOLTAGE, NEGATIVE POLARITY, REGULATED POWER SUPPLY 2 Sheets-Sheet 1 Filed April 12, 1960 Jan. 5, 1965 R, G. LUEBBEN 3,164,766

HIGH VOLTAGE, NEGATIVE POLARITY, REGULATED POWER SUPPLY Filed April l2, 1960 2 Sheets-Sheet 2 swr, ELL.

Fig. 4

INVENTOR.

' R`|CHARD G. LUEBBEN Fig. 5

United States Patent The present invention relates generally-to power supplies and more particularly to a high voltage, negative polarity, regulated power supply.

The primary object of this invention is to provide a power supply having ya high voltage, negative polarity output with a minimum oi ripple, yet without the necessity for extensive shielding around certain ot the components. The circuit utilizes transformer and iilter components of' novel construction in a specific arrangement which balances stray capacities in the circuit, the unbalance of which causes ripple.

Another object of this invention is to provide a high voltage power supply in which a virtually ripple free output is obtained without the use of high gain feedback circuits.

A further object ofthis invention is to provide a power supply whichis particularly suitable for use with klystrons requiring a high voltage input of negative polarity, an adaptation which necessitates the unregulated portion of the circuit` to be iioating, or not connected directly to ground. The stray capacities to ground inherent in such an arrangement are balanced and their etiectsvirtually f eliminated by the novel arrangementof the circuit.

Finally, itis an object to provide a high voltage power supply of the `aforementioned character which is simple and convenient to assemble and install and which will give generally etlicient and durable service.

With these and other objects definitely in View, this inventionconsists in the novel construction, combination and arransement of elements and portions, as will be yhereinafter fully described in the specilication, particularly pointed out in the claims, and illustrated in the drawingswhich form a material part of this'disclosure, and in` wl'iich:`

FlGURE 1 is aschematic wiring diagram of the complete power supply;

FGURE 2 is a diagrammatic View showing the arrangementof windings on the power transformer;

Flr/SURE 3 is a diagrammatic view showing the arrangement of windings on the filter inductance;

FGURE 4 is a diagram-ot a conventional type iilter circuit; and

FlGURE 5 is a diagram of a `modified lter circuit as used in the present power supply.

Similar characters of reference indicate similar or identical elements and yportions throughout the specification and throughout the views of the drawings.

Ziddtijlii output is of negative polarity, the entire power supply itl .is floating, that is, neither the positive nor negative terminal is connected to ground, in order that the voltage regulating circuit can be connected between the positive terminal and ground. In suchy an arrangement, ythe secondary windings Zd and 25, the terminals of rectifier stage Eil and input of ilter inductance 52 all have stray capacities to ground, the resultant voltages appearing in the regulating circuit being `coupled to the output 3d through a capacitor (hereinafter referred to as 73) and appearing as ripple in the iinal output. Normally, such ripple is removed by enclosing the pertinent components in a box type shield or shields, insulated from ground and connected to a point common to the anode 44 of tube 3S,

"so `that all leakage returns to the sour-ce, bypassing the output. Box type shields enclosing transformer secondary windings and filter windings are expensive, becausethey are not easily adaptable, fabrication wise, to production techniques land also tend to reduce reliability since they threaten dielectric strength in high voltage areas. Further, shields tend to increase size and weight andare consequently uneconornical.

Mechanical shielding can be avoided by balancingk the stray capacities in the circuit. in the transformer 14 this is accomplished by a particular method of applying the windings, as illustratedy in FGURE 2, the various terminals beingindicated byletters for identilication with the corresponding terminals in FlGURl-E 1. The primary winding 18 is wound irst on a coil winding mandrel, as well known in the art, the secondary windingfZdthen being4 applied with the start of thegsecondaryfwinding immediately over the iinish of the primary winding and wound in the same direction, resulting'in similar polarities, as indicated by the directional arrows.'k T he separate The circuit includes two basic units,vaf power supply',

lll and avoltage regulator l2, the voltage regulatorportion being, for the most part, conventional.- The power supply includes a transformer 15t- `having a grounded core id, a pair of primary windings lli andy 2li connected in` Cil,

The voltage regulator l2 includes ka tube lo which,

brieily, is coupled to the youtput 3o to regulate the high `voltage outputfin accordance w' l1y a 'reference derived from an auxiliary power input dil. Since the high voltage primary winding 2i! is next wound but, beiore'applying the secondary winding Zd, the mandrelis reversed,ktjhe start of said secondarywindingbeing placed immediately over the inish of said primary winding as before, Due to the mandrel reversal, however, the polarities of windings 2@ and ZS are reversed, as indicated by directional arrows, Vbut inter-winding capacity balance is not unduly affected. rrThe completed coils are` placed on the core 16 with the primary windings 13 yand 2? 'connected in parallel aiding arrangement to terminals A and B for connection tcinput terminals `23,2 and 24, respectively. The secondary windings 2o and 28 are connected in series between' terminals Cand E,-their common center connection being terminal D, which is effectively the electrical center oi `the balanced wave, having steep `leading and .trailing edges, the` harmonic energy in this type of waveform causes the secondary windings to oscillate with a "damping exponent such that four-to six cycles are seen. At these frequencies, usually yabout two decades above the input frequency, balance is diiiicult to achieve due to the lack of identical frequency-phase characteristics. To prevent oscillation, RC damping networks are coupled between the central terminal D andfterminals C and E( The damping networks each includea resistor iti and capacitor the resistors being of equal value and chosen to produce somewhat greater than critical damping at the respective terminals, thereby eliminatingoscillation. The

' capacitors i3 are ylikewise of equal value and act as fre- 'quency switches bysminirnizing power dissipation across nightly tances.

snes-,vee

quency of thev transformer. The inherent capacities present in the transformer 14 are indicated by hypothetical broken line capacitances Sti and 52.

The rectifier stage 30 comprises four diodes 54 arranged symmetrically with one in each side of the transformer output and the other two cross coupled across the output from terminals C and E, such an arrangement being substantially conventional. Other types of rectification may be used, the primary requirement being a symmetrical configuration to preserve balance. The inherent capacities to ground from the terminals of the rectifier stage 30 are indicated by hypothetical broken line capacitances 56 and 57, these being balanced due to the symmetrical arrangement.

The balancing of transformer 14 may be explained as follows: The potential instanteously produced between terminals C and D is equal and opposite in polarity to that produced between terminals D and E. Each of the capacitances S6 is effectively in series with the capacitance 50, while each capacitance 57 is similarly effectively in series with the capacitance 52. Thus currents will flow between terminals C and E by way of the inherent capaci- Since these capacitances are balanced, alternating currents are contained within the susceptance paths of the balanced capacitances and do not seek additional routes to provide potential equilibrium.

The balanced ilter inductance 32 has a grounded core 58 on which are two windings 60 and 62, the winding 6ft having an input terminal F and an output terminal G and the Winding n2 having an input terminal H and an output terminal I. As illustrated in FIGURE 3, the windings 6i? and 62 are applied so that their polarities are opposed, thus balancing the capacitance of the lter. In a conventional type of filter illustrated in FIGURE 4, two windings 64 and 66 are placed in series on a core 68, the windings being in one side of the circuit, and a capacitor '70 is connected between the output end of the windings and the other side of the circuit. For comparison, the filter inductance 32 is arranged in a corresponding manner in FIGURE 5, and it can be seen that the windings 60 and 62 are connected in series aiding configuration, one in each side of the circuit, a capacitor 72 being coupled across the output ends of the windings between terminals G and J.

The negative potential from terminal G is fed through V the final filter 3d, which has a single winding 74 on a grounded core 76, and then to the output 36. The posir tive terminal I is coupled, through a capacitor '78, to

the output end of winding 7d.

38 is connected directly to the positive side of the power supply at the junction of capacitor 72 and terminal J. The screen tt) of tube 38 is connected to the input 4d through a resistor S2. and the screenpotential is'regulated by a Zener diode S4 between said screen and ground, said diode also providing the reference for regulation of the negative high potential output. The grid 86 of tube 38 is coupled to the negative output between output 36 and filter 34 through a resistor SS and capacitor 9d and is further connected to ground through a Zener diode 92. The screen titi is connected through resistors 94, 96, 98 and Mii) in series, to the output 36, resistor 94 being variable to adjust for tolerances in Zener diode 84. Resistor 98 is also variable and the moving arm 102 thereof is coupled to the grid 86 through a tixed resistor 104, which is used to isolate the grid from resistor 9S, since this resistor is in effect a potentiometer control and may be located remotely from the power supply for control Lof output potential. Resistors 594-160 are of such values that the negative youtput potential at output A36, the plate potential of tube 3S and the potential across capacitor 78 are all in equilibrium at a given load current. Any ripple is coupled to the grid 36 through capacitor 90 and causes the anode d4 to respond with an almost equal and'opposite cancelling signal, with the result that the output is virtually ripple free. Resistor 8S and Zener diode 92 protect the grid 86 during turn on and .turn off when the capacitor 9i? charges and discharges. While the particular voltage regulator l2 is ideally suited for the purpose, other means of voltage regulation may be employed.

lf necessary, grounded eddy current shields may be placed around therwindings of transformer 14 and filter 32 to avoid interference from adjacent parts or equipment, but this may not be necessary in all applications.

rlhe negative high potential at output 36 is ideal for klystron beam potential supply, represented by the load ldd, in which ripple causes frequency modulation and drift and is therefore undesirable. Except for the specially wound transformer id and filter inductance 32, which can be made on conventional equipment, all components are conventional, the entire circuit being simple and compact'.

The operation of this invention will be clearly comprehended from a consideration of the foregoing description of the mechanical details thereof, taken in connection with the drawings and the above recited objects. It will be obvious that all said objects are amply achieved by this invention.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawings are to be considered as merely illustrative rather than limiting.

I claim:

1. A high voltage, negative polarity power supply, comprising: a low-ripple balanced transformer having a grounded core; a first primary Winding and a first secondary winding on said core and having similar polarity; a second primary'winding and a second secondary winding on said core and having opposite polarity; said primary windings being interconnected in parallel aiding relation and being connected to a source of power input; said secondary windings being connected in series aiding relation, whereby said transformer produces high voltage low-ripple AC. potential; RC damping networks coupled between the ends `of said secondary windings and their common center connection; rectifier means connected across said series-connected secondary windings for converting said AC. to DC.; a grounded core balanced filter having a first inductance winding connected in series between the negative side of said rectifier means and a negative output terminal, and a second inductance winding connected in series between the positive side of said rectifier means and a positive output terminal; said inductance windings being `of opposite polarity; a capacitor coupled across the output terminals of said inductance windings; a high Voltage output connected to said nega,- tive output terminal; both positive and negative sides of the power supply being electrically insulated from ground; voltage regulating means connected between said positive output terminal and ground; and a load connected between said hiUh voltage output and ground.

2. A high voltage, negative polarity power supply, comprising: a low-ripple balanced transformer having a grounded core; a rst primary winding and a first secondary winding on said core and having similar polarity; a second primary winding and a second secondary winding on said core and having opposite polarity; said primary windings being interconnected in parallel aiding relation and being connected toa source of power input; said secondary windings being connected inseries aiding relation, whereby said transformer produces high voltage low-ripple A.C. .potenalg rectiflermeans connected across said series-connected secondary windings for converting said A.C. to DC.; a grounded core balanced filter having a first inductance winding connected in series between the negative side of said rectifier means and a negative output terminal, and a second inductance winding connected in series between the positive side of said rectifier means and a positive output terminal; said inductance windings being of opposite polarity; a capacitor coupled across the output terminals of said inductance windings; a high voltage output; a final filter having an inductance winding connected in series between said negative output terminal and said high voltage output; a capacitor coupling said positive output terminal to a point between said final filter and said high voltage output; both positive and negative sides of the power supply being electrically insulated from ground; voltage regulating means connected between said positive output terminal and ground; and a load connected between said high voltage output and ground.

3. A high voltage, negative polarity power supply, comprising: a low-ripple balanced transformer having a grounded core; a first primary winding and a first secondary winding on said core and having similar polarity; a second primary winding and a second secondary winding on said core and having opposite polarity; said primary windings being interconnected in parallel aiding relation and being connected to a source of power input; said secondary windings being connected in series aiding relation, whereby said transformerproduces high voltage low-ripple A.C. potential; RC `damping networks coupled between the ends of said secondary windings and their common center connection; rectifier means connected across said series-connected secondary windings for converting said A.C. to DC.; a grounded core balanced filter having a first inductance winding connected in series between the negative side of said rectifier means and a negative output terminal, and a second inductance winding connected in series between the positive side of said rectifier means and a positive output terminal; said inductance windings being of opposite polarity; a capacitor coupled across the output terminals of said inductance windings; a high voltage output; a final filter having an inductance winding connected in series between said negative output terminal and said high voltage output; a capacitor coupling said positive output terminal to a point between said final filter and said high voltage output; both positive and negative sides of the power supply being electrically insulated from ground; voltage regulating means having one terminal thereof connected to said positive output terminal; and a load connected between said high voltage output and the other terminal of said voltage regulating means.

4. A power supply according to claim 3, wherein said first secondary winding is started at the finish of said first primary winding and wound in a common direction therewith; said second secondary winding being started at the nish of said second primary winding and wound in the opposite direction thereto; the ends or" like polarity of said primary windings being interconnected; and one end of said first secondary winding being connected to the end of opposite polarity of said second secondary winding.

5. A low-ripple, floating power D.C. supply, comprising: a transformer having a first primary winding and a first secondary winding of similar polarity, and having a second primary winding and a second secondary winding of opposite polarity, said primary windings being connected in parallel aiding relation and said secondary windings being connected in series aiding relation, whereby the inherent stray and distributed capacities between said windings tend to be minimized and balanced; means for converting the A.C. output from said composite secondary winding to D.C. energy, said means comprising a balanced rectifier connected across the ends of the composite secondary winding, whereby said rectifier has a negative output terminal and a positive output terminal; balanced filtering choke means for further reducing ripple in a balanced manner, said filtering choke means comprising a first inductance having one end thereof connected to said negative output terminal of said rectifier, and a second inductance having one end thereof connected to said positive output terminal of said rectifier; a load; a connection between the other end of one of said inductances and one end of said load; and a regulator circuit connected between the other end of said load and the other end of said other inductance, whereby any residual ripple is further minimized by said regulator circuit.

6. A low-ripple, floating power D.C. supply, comprising: a transformer having a first primary winding and a first secondary winding of similar polarity, and having a second primary winding and a second secondary winding of opposite polarity, said primary windings being connected in parallel-aiding relation and said secondary windings being connected in series-aiding relation, whereby the inherent stray and distributed capacities between said windings tend to be minimized and balanced; means for damping harmonic oscillations produced in said secondary windings, said means comprising a series-connected resistance-capacitance network connected across each said secondary winding; means for converting the AC. output from said secondary winding to DC. energy, said means comprising a balanced Irectifier connected across the ends of the composite secondary winding, whereby said rectifier has a negative output terminal and a positive output terminal; balanced filtering choke means for further reducing ripple in a balanced manner, said filtering choke means comprising a first inductance and a second inductance mounted on a common core, one end of said first inductance being connected to said negative output terminal of said rectier, and one end of said second inductance being connected to said positive output terminal of said rectifier; a load having one end grounded; a third inductance connected between the other end of said first inductance and the ungrounded end or said load; and a regulator circuit connected between ground and the other end of said sec-- ond inductance, whereby any residual ripple is further minimized, said load and said regulator circuit being grounded while said power supply is not grounded.

References Cited bythe Examiner UNITED STATES PATENTS 1,504,276 S/24 Shackelton 336-69 1,827,191 10/31 Casper 336-69 2,291,069 7/42 Brown 321-9 2,546,657 3/51 Smoot 336-30 X 2,564,221 S/Sl Hornfeck 336-30 2,568,587 8/51 MacGeorge 336-136 2,878,441 3/59 Rogers et al. 323-44 2,891,214 6/59 Rogers et al 323-44 2,895,059 7/59 Bell 321-9 X 2,914,719 11/59 VJalton et al 321-8 3,037,159 5/62 Brown 321-18 LLOYD MCCOLLUM, Primary Examiner.

SAMUEL BERNSTEIN, MILTON O. HIRSHFIELD, Examiners. 

1. A HIGH VOLTAGE, NEGATIVE POLARITY POWER SUPPLY, COMPRISING: A LOW-RIPPLE BALANCED TRANSFORMER HAVING A GROUNDED CORE; A FIRST PRIMARY WINDING AND A FIRST SECONDARY WINDING ON SAID CORE AND HAVING SIMILAR POLARITY; A SECOND PRIMARY WINDING AND A SECOND SECONDARY WINDING ON SAID CORE AND HAVING OPPOSITE POLARITY; SAID PRIMARY WINDINGS BEING INTERCONNECTED IN PARALLEL AIDING RELATION AND BEING CONNECTED TO A SOURCE OF POWER INPUT; SAID SECONDARY WINDING BEING CONNECTED IN SERIES AIDING RELATION, WHEREBY SAID TRANSFORMER PRODUCES HIGH VOLTAGE LOW-RIPPLE A.C. POTENTIAL; RC DAMPING NETWORKS COUPLED BETWEEN THE ENDS OF SAID SECONDARY WINDINGS AND THEIR COMMON CENTER CONNECTION; RECTIFIER MEANS CONNECTED ACROSS SAID SERIES-CONNECTED SECONDARY WINDINGS FOR CONVERTING SAID A.C. TO D.C.; A GROUNDED CORE BALANCED FILTER HAVING A FIRST INDUCTANCE WINDING CONNECTED IN SERIES BETWEEN THE NEGATIVE SIDE OF SAID RECTIFIER MEANS AND A NEGATIVE OUTPUT TERMINAL, AND A SECOND INDUCTANCE WINDING CONNECTED IN SERIES BETWEEN THE POSITIVE SIDE OF SAID RECTIFIER MEANS AND A POSITIVE OUTPUT TERMINAL; SAID INDUCTANCE WINDINGS BEING OF OPPOISTE POLARITY; A CAPACITOR COUPLED ACROSS THE OUTPUT TERMINALS OF SAID INDUCTANCE WINDINGS; A HIGH VOLTAGE OUTPUT CONNECTED TO SAID NEGATIVE OUTPUT TERMINAL; BOTH POSITIVE AND NEGATIVE FROM OF THE POWER SUPPLY BEING ELECTRICALLY INSULATED FROM GROUND; VOLTAGE REGULATING MEANS CONNECTED BETWEEN SAID POSITIVE OUTPUT TERMINAL AND GROUND; AND LOAD CONNECTED BETWEEN SAID HIGH VOLTAGE OUTPUT AND GROUND. 